Lately, cloud computing has been introduced that may provide computing as a service using resources distributed over a network. For example, cloud computing may provide computation, software applications, data access, data management, and storage resources without requiring users to know the location and other details of the computing infrastructure. Such cloud computing can be defined as on-demand outsourcing service provided through a communication network. In a cloud computing environment, a service provider may form cloud centers by virtually integrating resources distributed over a communication network and provide a cloud service to a user through the cloud centers. Such a cloud center may be a basic unit to provide a cloud service in cloud computing environment. In order to provide the cloud service to a client, the cloud center may create at least one virtual machine using associated resources, such as a computing node and a storage node.
A plurality of cloud centers distributed over global regions may form a global cloud center network. Since cloud centers are distributed over global regions in a global cloud center network, the global cloud center network may have high fault tolerance because of geographical characteristics. For example, in general, a processing load of a cloud center may be high during the day time and low at night time. A cloud center located at Seoul, Korea may have a high processing load at a day time. In this case, a cloud center located at New York, U.S. may be allocated to users to provide the cloud service because the cloud center is located at New York during night time. For another example, a cloud center located at Tokyo, Japan may not be in operation due to an earthquake or other malfunction. In this case, a cloud center located in Seoul, Korea may be allocated to a client to provide the cloud service. As described above, a global cloud center network may have many merits and efficiently provide a cloud service to clients.
Lately, the problems of global warming have received great attention from the general public and scientific community. The International environmental treaty, United Nations Framework Convention on Climate Change (UNFCCC), has defined the Kyoto protocol in order to attempt to reduce further climate change. The Kyoto protocol defines a carbon emission credit, provides a mechanism for allocating carbon credits to countries, and countries are regulated to emit a green house gas, such as a carbon-dioxide and a carbon monoxide gas, based on their allocated carbon emission credits. A lot of effort has been made to reduce emission of green house gas in various fields.